Automatic commutator-adjuster for dynamo-electric machines



{No Model.)

E/THOMSON.

AUTOMATIC GOMMUTATOR ADJUSTER FOR DYNAMO ELECTRIC MACHINES.

No. 328,976. Patented Aug. 11, 1885.

N. PETERS. Pnowumo n her, Washinghlx I10.

NrTnn STATES PATENT rrrea,

ELIHU THOMSON, OF LYNN, MASSACHUSETTS.

AUTOMATIC COMMUTATOR-ADJUSTER FOR DYNAMO-ELECTRIC MACHINES.

SPECIFICATION forming part of Letters Patent No. 323,976, dated August11, 1885.

Application filed April 2, 1885.

(No model.)

To all whom, it may concern.-

Be it known that I, ELTI-IU TnoMsoN, a citizen of the United States, anda resident of Lynn, in the county of Essex and State of Massachusetts,have invented a certain new and useful Automatic (lominutator-Adjusterfor Dynamo-Electric Machines, of which the following is a specification.

The object of my invention is to prevent sparking at the commutators oidynamo-electric machines. It is well known in the operation of suchmachines that when the strength of the current delivered from thearmature of the machine changes through any difference in the resistanceof the circuit due to differences in the number of lamps or otherdevices in operation, the so-called neutral lineshifts, and if thebrushes be unadjusted to follow such shifting a sparking will occur atthe commutator.

My invention consists in automatically shiftin g the brushes, to followthe shifting neutral line, through the agency of a load or straindetector applied to the. driving-power of the machine in such way thatthe increase of load put upon the driving-power by increase in thecurrent delivered from the armature shall be felt, and shall cause anautomatic adjustment of the commutator-brushes or commutator-cylinder inthe properdiree tion to avoid spark.

My invention is particularly applicable to dynamo-electric machines whenused for incandescent lighting or other purposes where, through thevariations in the number of translating devices in use, the currentstrength of the machine is subject to changes. Any device whereby theload imposed upon the driving-power in operating the dynamo may bedetected or felt may be employed in carrying out my invention, it onlybeing necessary to connect such load or strain detector through suitableintermediate mechanism with the moving parts of the adjustablecommutator in such way that the movement of the load or strain detector,consequent upon an increase in the power required to drive the dynamo,shall eiiect an adjustment of the commutator.

Some of the ways in which my invention may be carried out areillustrated in the accom pan yin g drawin Figure 1 is an elevation ofapparatus simply formed, in which. the devices are combined according tomy invention for the purpose of moving the comnmtator-brushes. Fig. 2illustrates an arrangement whereby an adjustment of thecommutator-cylinder may be eftected in obedience to chan ,qes in theload put upon the driving-power. Fig. 3 is an elevation of a detail ofconstruction.

Referring to Fig. 1, A indicates the ar1na ture of a dynamo electricmachine; K, the commutator; Y, the yoke that carries thecommutator-brushes, and that may, as usual, be shifted to move thebrushes backward and forward upon the commutator-eylinder.

Gr indicates an outside or working circuit connected .to the commutatorand supplying incandescent lamps or other devices in multiple are afterthe usual manner.

The field-of-force magnet of the machine is indicated at M, and is hereshown as corn nected in a derived circuit of high resistance to theoutside or working circuit after a wellknown manner.

The commutator K is of any desired type, and is connected, as usual, tothe coils upon the armature A. The winding of the field-mag nets M isimmaterial, and may be a series winding, shunt winding, or compoundwinding.

The yoke Y is connected by a link with the lever L, carrying anidler-pulley, I, that bears upon the belt B, and serves to move the yokeand brushes in obedience to varying strains put upon the belt throughvariations in the load. The spring S, applied to the lever, causes thepulley to bear upon the belt, so that the varying tension of the beltmay move the lever.

It is desirable to have a second idler, I, (indicated in dotted lines,)carried from a fi ame suspended from the lever L, so as to take up theslack of the belt on the side B when the idler I yields to the increasedstrain on the side 13. The adjustments are made such through change ofleverage or otherwise that when the load is light, due to the number oflights or. other devices upon the circuit G being small, the drivingstrain on the belt B being correspondingly small, the brushes carriedupon the yoke Y will be upon the proper neutral line of the commutatorto prevent sparkin \Vhen, however, the number of lights or other devicessupplied in multiple are from the circuit G is increased, thus decreasng the resistance for the armature, demanding more current and puttingmore load upon the machine, the belt B will become more tense, and theidler-pulley I will be raised, so as to move thelever L and shift thecommutator-brushes forward, so as to follow the shifting neutral line,which, as is well un- IO derstood, will move forward with the increasedcurrent and load. In a similar way a backward movement will occurthrough the action of the spring S when the load decreases, so as tofollow the shifting neutral line in a backward direction.

Fig. 1 is an example only of a way of applying my invention, and I donot by any means confine myself to the particular set of devices thereshown.

In Fig. 2 I haveillustrated another construction of load or straindetector'and another way of applying the same to the commutator so as toeffect an adjustment of the latter in correspondence with variations ofload. In 2- the latter instance the arrangement is such that thecommntator-cylinder may be adjusted instead of the commutator-brushes.In either case, however, it is to be understood that the commutator isadjusted, and by ad' 0 justable commutator I mean any commutator soconstructed that either the brush or commutator cylinder may be adjustedso as to fol low the shifting neutral line.

The brushes B are supposed to be fixed 5 and set by hand in the positionrequired for normal work. The commutator-cylinder K is, however, looseupon the shaft, and is connected with devices, to be presentlydescribed, whereby it may be shifted backward on in- 0 crease of load,so as to produce the same adjustment in effect as would be produced byshifting the brushes forward in the direction of revolution.

The armature A is loose upon the drivingshaft X, and the connectionsfrom the coils thereof to the connnutatorcylinder K are made flexible,so as to permit the movement of one with relation to the other. Thearmature is driven from a pulley, P, fixed upon the shaft X through thesprings S S or other flexible yielding devices, which connect saidpulley with a disk, I), or other device secured to the armature. Thisarrangement constitutes a load or strain detector, and permitsan'angular movement of the armature-shaft X and pulley P with relationto the armature upon an increase of the load. The springs S areconnected to pins or studs borne by disks, which are respectivelyfastened rigidly to the armature A and the pulley I In .liig. 3 thestuds (1 d are supposed to be those carried by the disk D, and thestudspp are attached to the disk carried by the pulley 1. The springs SS are attached at one end 6 to the studs d, and at the other to thestudsp. The obvious result of attempting to rotate the pulley 1 will beto extend the springs S with 5 a force depending on the opposition ofthe armature to rotation in its magnetic field.

The relative angular movement of the shaft X and pulley P withrelationto the armature isimparted, through aset of gears(indicated at Ganalogous to the back gear of a lathe, to the commutatorcylinder. Otherdevices than those shown may be employed for imparting such movement;but those indicated form an effective and simple device, and alsoprovide for imparting a magnified movement to the commutator-cylinder K.

The gear-wheels c b are carried upon a shaft mounted in an arm extendingfrom the driving shaft X and gear, respectively, with a wheel,f,connected to the commutator-cylinder, and with a wheel, a, connected tothe armature. A counter-poise-weight, V, for keeping the parts balancedduring rotation, is preferably provided. The wheel 0 is made larger indiameter than the wheel Z).

The operation of this arrangement is as follows: \Vhen an increasedcurrent is developed in the armature A from any causeas, for instance,by increasing the number of devices in multiple are upon the circuitfrom said armature-an extension of the springs S S to a greater degreeis caused, and a movement of the shaft X with relation to the arm aturcoccurs, thus causing a movement of the arm carrying the gears e I) and arotation of said gears in such direction as to move thecommutator-cylinder backward in a direction opposite to the direction ofrotation, thus bringing the point of neutrality into coincidence withthe fixed brushes, assuming them to have been correctly set at thestart.

In dynamo-electric machines of mosttypes a shifting of the neutral linetakes place in a forward direction corresponding to the direction ofrotation of the armature upon an increase of the current or load due toincrease of the number of lamps in multiple are.

My invention provides an effective means of weighing the increased load,and imparting to the commutator an adjustment in the proper direction tomeasurably compensate for the shifting of the line upon which brushesshould bear, in order that little or no sparks may 0((3111 upon thecommutator-cylinder.

By the term load or strain detector I mean any mechanical deviceswhereby the increased resistance of the armature to rotation may beindicated, or may work a movement of parts from which movement may becommunicated to the connnutator in proper direction to compensate forshifting of the neutral line.

I claim as my invention- 1. The combination, substantially as described,of an adjustable commutator and a load or strain detector combined withsaid commutator and controlling the adjustment thereof in accordancewith the shifting in position of the neutral line, so that on a shiftingof the neutral line by difference in strain or load the commutator shallbe automatically set or adjusted to follow such shifting.

2. The combination, with a dynamo-electric machine, of an adjustablecommutator, a load or strain detector, and devices controlled therebyfor varying the set or adjustment of the commutator in the properdirections to compensate for the shifting of the neutral line.

3. The combination, with a dynamo-electric machine Whose armaturesupplies electric lamps or other devices in multiple are, of anadjustable commutator, a load or strain detector, and mechanism operatedthereby and connected with the commutator, as described, and controllingthe set or adjustment of the same, in the manner described, so as tofollow the shifting of the neutral line.

4. The combination, with a dymuno-electric machine or generatorsupplying lamps or other devices in multiple arc, and having itsfield-magnet coils in a derived circuit, of an adjustable commutator, aload or strain detector, and mechanism connected with the same and wi hthe commutator, in the manner described, to cause an adjustment in aforward direction, to compensate for a shifting forward of the neutralline when an increase in the current delivered by the armature takesplace.

5. The combination, With the armature and its driving-shaft or pulley,movable With relation to one another in an angular direction, of anintermediate spring or springs and a commutator-cylinder loose upon thedrivingshaft, and connected with said shaft through devices whereby itmay be adjusted in a backward direction on an increase of load.

Signed at Lynn, in the county of Essex and State of Massachusetts, this27th day of March, A. D. 1885.

ELIHU THOMSON.

Witnesses:

M. L. THoMsoN,

W. O. WAKEFIELD.

